1. Field of the Invention
The present invention relates to an image processing apparatus, a data amount reducing method, and a data amount reducing program embodied on a computer readable medium. More particularly, the present invention relates to an image processing apparatus, a data amount reducing method, and a data amount reducing program embodied on a computer readable medium which reduce a data amount of image data to a desired amount.
2. Description of the Related Art
In recent years, image data which are read from originals by scanners or the like are transmitted via e-mail or the like. In data transmission via e-mail or the like, the data amount that can be transmitted at a time may be restricted in order to reduce the load on the network. In the case where the data amount of the image data is large, it is necessary to reduce the data amount of the image data so as not to exceed the limited amount. As a technique of reducing the data amount of image data, for example, Japanese Patent Laid-Open No. 2005-204206 discloses an image processing apparatus, in which the image data is separated into character images including characters and photograph images including graphic patterns or photographs other than the characters, and the character images are subjected to binarization and then modified modified READ (MMR) compression, while the photograph images are subjected to Joint Photographic Experts Group (JPEG) compression.
In the conventional image processing apparatus, however, all the character portions included in the image data are subjected to binarization, and all the photograph portions included in the image data are subjected to JPEG compression, which leads to degradation of image quality in both the character portions and the photograph portions. Binarization of the character portions may blur the characters to make them illegible. JPEG compression of the photograph portions will lead to degradation of image quality. Image data may include important portions that the user thinks to be important and unnecessary portions that the user does not think to be important. While it may not matter much when the unnecessary portions suffer degradation of image quality, it is desirable that good image quality is maintained for the important portions.